Auto merge of #9116 - adrianheine:patch-1, r=jdm
Auto merge of #9116 - adrianheine:patch-1, r=jdm

Update virtualenv package name for Debian systems

Since Debian Jessie (current stable), the executable is in a `virtualenv` package.

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ConnorGBrewster/servo,cbrewster/servo,anthgur/servo,KiChjang/servo,thiagopnts/servo,nnethercote/servo,canaltinova/servo,szeged/servo,steveklabnik/servo,KiChjang/servo,nrc/servo,eddyb/servo,canaltinova/servo,jimberlage/servo,larsbergstrom/servo,dsandeephegde/servo,paulrouget/servo,SimonSapin/servo,fiji-flo/servo,paulrouget/servo,fiji-flo/servo,rnestler/servo,nnethercote/servo,eddyb/servo,szeged/servo,emilio/servo,paulrouget/servo,upsuper/servo,jimberlage/servo,CJ8664/servo,peterjoel/servo,DominoTree/servo,steveklabnik/servo,anthgur/servo,emilio/servo,anthgur/servo,notriddle/servo,anthgur/servo,rnestler/servo,peterjoel/servo,thiagopnts/servo,saneyuki/servo,dsandeephegde/servo,emilio/servo,paulrouget/servo,dsandeephegde/servo,notriddle/servo,thiagopnts/servo,splav/servo,steveklabnik/servo,sadmansk/servo,dati91/servo,pyfisch/servo,notriddle/servo,peterjoel/servo,rnestler/servo,sadmansk/servo,szeged/servo,splav/servo,cbrewster/servo,splav/servo,cbrewster/servo,saneyuki/servo,mbrubeck/servo,larsbergstrom/servo,upsuper/servo,larsbergstrom/servo,saneyuki/servo,sadmansk/servo,rnestler/servo,saneyuki/servo,peterjoel/servo,nnethercote/servo,upsuper/servo,peterjoel/servo,dsandeephegde/servo,saneyuki/servo,saneyuki/servo,eddyb/servo,ConnorGBrewster/servo,steveklabnik/servo,SimonSapin/servo,saneyuki/servo,rnestler/servo,rnestler/servo,dati91/servo,upsuper/servo,fiji-flo/servo,thiagopnts/servo,eddyb/servo,steveklabnik/servo,emilio/servo,mbrubeck/servo,sadmansk/servo,pyfisch/servo,mbrubeck/servo,rnestler/servo,KiChjang/servo,dati91/servo,mattnenterprise/servo,SimonSapin/servo,KiChjang/servo,mbrubeck/servo,avadacatavra/servo,thiagopnts/servo,SimonSapin/servo,dati91/servo,nrc/servo,CJ8664/servo,thiagopnts/servo,DominoTree/servo,avadacatavra/servo,ConnorGBrewster/servo,mattnenterprise/servo,dsandeephegde/servo,larsbergstrom/servo,pyfisch/servo,CJ8664/servo,canaltinova/servo,jimberlage/servo,dati91/servo,canaltinova/servo,eddyb/servo,szeged/servo,SimonSapin/servo,upsuper/servo,splav/servo,canaltinova/servo,larsbergstrom/servo,splav/servo,DominoTree/servo,dati91/servo,pyfisch/servo,DominoTree/servo,cbrewster/servo,avadacatavra/servo,larsbergstrom/servo,avadacatavra/servo,ConnorGBrewster/servo,paulrouget/servo,sadmansk/servo,KiChjang/servo,ConnorGBrewster/servo,splav/servo,anthgur/servo,splav/servo,cbrewster/servo,notriddle/servo,pyfisch/servo,saneyuki/servo,nnethercote/servo,sadmansk/servo,SimonSapin/servo,larsbergstrom/servo,peterjoel/servo,emilio/servo,szeged/servo,nnethercote/servo,larsbergstrom/servo,mattnenterprise/servo,splav/servo,upsuper/servo,ConnorGBrewster/servo,larsbergstrom/servo,pyfisch/servo,avadacatavra/servo,jimberlage/servo,dsandeephegde/servo,fiji-flo/servo,CJ8664/servo,steveklabnik/servo,notriddle/servo,CJ8664/servo,szeged/servo,CJ8664/servo,mbrubeck/servo,KiChjang/servo,notriddle/servo,splav/servo,szeged/servo,paulrouget/servo,KiChjang/servo,nnethercote/servo,fiji-flo/servo,steveklabnik/servo,DominoTree/servo,ConnorGBrewster/servo,mattnenterprise/servo,jimberlage/servo,jimberlage/servo,larsbergstrom/servo,eddyb/servo,KiChjang/servo,splav/servo,dsandeephegde/servo,nrc/servo,rnestler/servo,cbrewster/servo,avadacatavra/servo,dati91/servo,peterjoel/servo,emilio/servo,SimonSapin/servo,paulrouget/servo,nnethercote/servo,notriddle/servo,pyfisch/servo,nrc/servo,szeged/servo,upsuper/servo,DominoTree/servo,pyfisch/servo,cbrewster/servo,nrc/servo,emilio/servo,CJ8664/servo,cbrewster/servo,pyfisch/servo,DominoTree/servo,CJ8664/servo,jimberlage/servo,szeged/servo,KiChjang/servo,fiji-flo/servo,avadacatavra/servo,eddyb/servo,dsandeephegde/servo,nrc/servo,DominoTree/servo,paulrouget/servo,mbrubeck/servo,saneyuki/servo,sadmansk/servo,upsuper/servo,notriddle/servo,canaltinova/servo,notriddle/servo,eddyb/servo,saneyuki/servo,paulrouget/servo,nnethercote/servo,canaltinova/servo,sadmansk/servo,szeged/servo,mattnenterprise/servo,mattnenterprise/servo,avadacatavra/servo,paulrouget/servo,anthgur/servo,emilio/servo,canaltinova/servo,mbrubeck/servo,nrc/servo,DominoTree/servo,peterjoel/servo,anthgur/servo,SimonSapin/servo,mbrubeck/servo,thiagopnts/servo,fiji-flo/servo,ConnorGBrewster/servo,fiji-flo/servo,dati91/servo,emilio/servo,KiChjang/servo,emilio/servo,notriddle/servo,pyfisch/servo,DominoTree/servo,thiagopnts/servo,mattnenterprise/servo,nnethercote/servo,jimberlage/servo,mattnenterprise/servo,jimberlage/servo,nnethercote/servo,peterjoel/servo,anthgur/servo,peterjoel/servo